To get epic set for your alt or yourself you need 36 Wintergrasp Commendations (or battlegrounds if you want it to yourself at endgame). WG Commendations can be bought by 30 Stone Keeper's Shard each making in grand total of 1080 shards, thats 270 heroic boss kills(4 each) when you have wintegrasp buff. Rare set needs only 12 Wintergrasp Commendations wich is 360 shards and thats 90 heroic bosses with WG buff.

Edit: math fail

Edit2: Cataclysm prices can be seen on the sells tab, above information is outdated now.

Comment by Nevalistis

Currently, none of the level 60 pvp gear is eligible for Transmogrification. However, it looks like it's being worked on. Players with the appropriate old school Feats of Strength will have an easier time acquiring the rarer gear from these sets for Transmogrification!